Improvement of gas exchange during high frequency intermittent oscillation in rabbits

Objective: Intermittent oscillatory flow has been reported experimentally to improve axial dispersion of respiratory gases by manipulating the flow waveform of oscillatory flow. We clinically investigated the improvement of high-frequency intermittent oscillation (HFIO). Methods: Seven male rabbits were anesthetized and controlled with conventional ventilation. Arterial blood gas was sampled to analyze PaO2, PaCO2, and other hemodynamic parameters after conversion to high-frequency oscillation (HFO) or HFIO. Results: There were no differences in PaO2 profiles between HFO or HFIO. Arterial CO2 levels were dependent on the tidal volume and waveforms. At the same tidal volume, HFIO resulted in better CO2 elimination than did HFO. CO2 expiration was significantly higher with HFIO. Conclusions: At a small tidal volume (2.0−2.5 ml/kg), gas exchange on the intermittent waveform is significantly higher than with sinusoidal waveforms. Intermittent waveforms are more efficient than are sinusoidal forms not only under normal conditions but also in the critically diseased lung.